There are several traditional methods of treating and disposing of waste. The choice of a particular treatment and disposal method depends primarily upon two factors: 1) the particular waste requiring treatment and disposal, and 2) the particular location within which the treatment and disposal facility must be installed. Of particular concern is the treatment and disposal of human waste, often referred to as sanitary waste, which contains bacteria, particularly fecal coliform bacteria, that poses a significant health hazard in excess concentration. The generation of sanitary waste often occurs in locations, such as remote or portable facilities, that present unique problems associated with treatment and disposal. Conventional waste treatment and disposal systems have been designed for these situations; however, conventional systems have several drawbacks.
Conventional waste treatment and disposal systems for remote and portable facilities typically comprise a large holding tank to receive and accumulate waste. The waste may be disinfected using appropriate chemicals and once disinfected, the waste is usually stored until it can be removed for further processing elsewhere. For portable facilities, such as vehicles, watercraft, aircraft and railroad cars, the waste must be stored until the portable facility reaches a waste receiving site. For remote facilities, particularly those in which traditional sewers and septic systems are impractical, the waste must be stored until such time that the waste can be removed and delivered to a waste receiving site. The need to store chemicals, as well as the treated waste, requires significant storage capacity and increases both the cost of constructing and operating the portable or remote facility.
In the case of watercraft, conventional treatment and disposal systems treat waste material with chemicals and/or indirect heat to destroy bacterial content. Once treated, the waste may be discharged into the environment. Chemical systems have a number of disadvantages, including the expense of the chemicals they employ and the noxious odors liberated with their use. Also, chemical systems are not always totally effective in killing bacteria, so that the discharged waste material may still cause pollution and environmental problems. Systems employing indirect heat to sterilize the waste material also have drawbacks, particularly the extremely large amount of heat transfer area required to adequately sterilize the waste and the potential need for chemical oxidizers and a fuel supply to generate the required heat, which both result in an increase of construction and operating expense.
In addition, increasingly strict environmental regulations prohibit the discharge of even treated waste material in certain areas, such as inland waterways and lakes. Conventional treatment and disposal systems cannot be used in these areas, thus requiring the installation of adequate storage capacity for holding the waste until a waste receiving site can be reached. The expense and inconvenience of having to locate and travel to a waste receiving site serves as an incentive to disregard regulations and discharge the holding tank directly into the environment, frustrating the purposes of the environmental regulations.
In U.S. Pat. No. 6,106,703, the named inventor herein disclosed a waste treatment and disposal system that utilized the exhaust of an internal combustion engine to dispose of sanitary and other types of waste. The disclosure of U.S. Pat. No. 6,106,703 is incorporated herein by reference. That patent generally discloses, a waste treatment system comprised of a holding tank for receiving waste generated from an input source, such as a head, galley, shower, bilge tank, or other similar source, at least one macerator connected to the holding tank, a reducer for decreasing the particle size of solid waste, a centrifugal separator, an injector pump, and an injector nozzle disposed within the exhaust manifold of an internal combustion engine.
The present invention improves upon the waste treatment and disposal system disclosed in U.S. Pat. No. 6,106,703 in several ways. The present invention simplifies system operation by utilizing a common energy source for fluid movement devices. Additionally, the present invention incorporates ozone generators and high frequency activators to condition waste prior to thermal treatment. The present invention also incorporates liquid/liquid and gas/liquid preheaters that thermally condition the waste prior to injection into an exhaust stream. Preheating the waste increases disposal efficiency and increases operational capacity limits. Significant improvements were made to the reducer, referred to herein as the homogenizer, including improvements to the sizing screen design, improvements to the blade design, modification of the device to allow reverse operation, addition of a recirculation inlet port, and external pumping capability. These modifications improved particle attrition and eliminate the need for solid waste separation devices, such as the centrifugal separator. The present invention also improves upon the injector design with the addition of an exhaust manifold spool piece that eliminates the need to modify existing exhaust manifolds. Finally, process control improvements are added, which along with the other modifications, improve overall system efficiency and performance and reduce the space required for installation of the system.